Blue diamonds are the cream of the crop right now, if auction results are anything to go by. A few weeks ago Sotheby’s Hong Kong announced the upcoming auction of the infamous De Beers Millenium Jewel 4. Weighing in at 10.10cts, this oval, flawless, fancy vivid blue diamond was auctioned on Tuesday 5th April for $31.8million, setting a record as the most expensive diamond ever auctioned in Asia.

Pre-sale estimates for the diamond were set in the $30 – $35million category, so the diamond sold closer to the lower end of this estimate. Nevertheless, it’s still a remarkable price for a remarkable diamond.

The diamond was targeted as part of the biggest planned jewel heist in history when it was on display at London’s Millenium Dome. The attempted robbery was foiled by the police after an anonymous tip-off allowed the police to replace the genuine diamonds with artificial replicas, ahead of the brazen attempt.

Natural blue diamonds are hot property at the moment, with a number of forth-coming auctions set to feature stones such as the 14.62ct Oppenheimer Blue Diamond and the 9.54ct Shirley Temple Blue Diamond.  Let’s not forget last year’s auction of the remarkable Blue Moon diamond, for a record $48.5million, a world record price for any diamond.

But what makes blue diamonds so special?

First and foremost is their rarity. The most common coloured diamonds mined are browns and greys, and any fancy colours will immediately fetch higher prices on the basis of their scarity. Cullinan Diamond Mine, in South Africa, is the world’s most renowned and reliable source of natural blue diamonds.

Blue diamonds occur naturally as a result of the incorporation of the element boron into the crystal lattice. The amount of boron will determine the intensity of the blue colour. The more vivid or intense the blue colour, the more expensive the stone will be. Combine an intense fancy colour with an outstanding size and clarity, and the market will clamour to pay millions.

Images: Isabel Infantes/SWNS